An amplifier arrangement with enhanced harmonic rejection

ABSTRACT

The present disclosure relates to an amplifier arrangement ( 1, 100, 200 ) comprising a first amplifier device ( 2, 102, 202 ) and a second amplifier device ( 3, 103, 203 ) where each amplifier device ( 2, 3; 102, 103; 202, 203 ) is connected to an input circuit ( 8, 108 ) and has a first type output terminal ( 4, 6 ; D) and a second type output terminal ( 5, 7 ; S), where the output terminals ( 4, 6 , D;  5, 7 , S) are connected to an output circuit ( 9, 109, 109 ′). The first type output terminal ( 4 , D) of the first amplifier device ( 2, 102, 202 ) is connected to the second type output terminal ( 7 , S) of the second amplifier device ( 3, 103, 203 ) by means of a first connection ( 10, 110 ), and the first type output terminal ( 6 , D) of the second amplifier device ( 3, 103, 203 ) is connected to the second type output terminal ( 5 , S) of the first amplifier device ( 2, 102, 202 ) by means of a second connection ( 11, 111 ). The first type output terminal ( 4 , D) of the first amplifier device ( 2, 102, 202 ) and the first type output terminal ( 6 , D) of the second amplifier device ( 3, 103, 203 ) are electrically separated in the output circuit ( 9, 109, 109 ′), and the second type output terminal ( 5 , S) of the first amplifier device ( 2, 102, 202 ) second type output terminal ( 7 , S) of the second amplifier device ( 3, 103, 203 ) are electrically separated in the output circuit ( 9, 109, 109 ′).

TECHNICAL FIELD

The present disclosure relates to amplifiers, in particular push-pullcircuit to amplifiers, where there is a desire to reject undesiredharmonics.

BACKGROUND

The number of frequency bands and hardware frequency variants has grownrapidly which has created a strong demand for wideband radios and poweramplifiers (PAs). A well-known problem with such wideband PAs is thatharmonic frequencies and intermodulation products, e.g. 2^(nd) ordertones such as baseband and 2^(nd) order harmonics, falls within thecarrier frequency band and can result in imminent performancedegradation. For example, baseband frequencies that fall within thefundamental band will face resistive terminations, resulting indistortion and lower efficiency. The same is true for 2^(nd) harmonictones within the fundamental band. In addition, intermodulation productsand harmonic tones within the fundamental band might requireband-specific filters in order to comply with emission standards. Such arequirement severely reduces the benefit of the wideband radio bycomplicating the design and deployment, and by requiring an inventory ofband-specific filters.

An uncomplicated solution to the described problem is operating the PAin class-A mode. When doing so, very low content of intermodulationproducts, such as baseband, and harmonic content is generated. Thedrawback is poor energy efficiency which in practice disqualifies suchsolution in most applications.

A more attractive method is the Push-Pull class-B amplifier. It is wellknown that such an amplifier configuration can differentiate betweencommon and differential mode, and it thereby has a theoreticalcapability to present ideal load terminations for both second ordertones and fundamental frequency even though they appear within the sameband. In other words; it allows e.g. the baseband tones, and the secondharmonic tones to be short-circuited even though they fall within theband where the fundamental tone is terminated in its ideal load.

In prior art FIG. 1 , the output currents Icm, Idm in a push-pullamplifier arrangement are indicated with dashed lines. Assuming thenetwork is symmetrical, i.e. Z11=Z22, the load impedance seen byamplifier devices, here represented as current sources I1, I2, becomesZL,d=Z11-Z12 at differential mode, and ZL,c=Z11+Z12 at common mode.

In the case of using complementary device techniques (n-type andp-type), the fundamental frequency is excited in common mode, and evenorder tones such as baseband and 2nd harmonics are excited indifferential mode The desired short-circuit impedance for even ordertones is then easily realized by letting Z11=Z22=Z12, see FIG. 1 .However, the limited performance of p-type transistors makes them a nooption in high performance RF/microwave applications. Using only n-typedevices, the situation becomes the opposite to what is described above,i.e. the fundamental frequency is excited in differential mode and evenorder tones are excited in common mode. Hence the output network in FIG.1 must fulfill Z11=Z22=−Z12 which is very challenging over a largebandwidth.

It is therefore desired to present a new type of circuit topology thatenables wideband capabilities of amplifiers that can be run as push-pullamplifiers.

SUMMARY

It is an object of the present disclosure to provide a circuit topologythat enables wideband capabilities of amplifiers that can be run aspush-pull amplifiers.

This object is obtained by means of amplifier arrangement comprising afirst amplifier device and a second amplifier device, where eachamplifier device is connected to an input circuit. Each amplifier devicehas a first type output terminal and a second type output terminal wherethe output terminals are connected to an output circuit. The first typeoutput terminal of the first amplifier device is connected to the secondtype output terminal of the second amplifier device by means of a firstconnection, and the first type output terminal of the second amplifierdevice is connected to the second type output terminal of the firstamplifier device by means of a second connection. The first type outputterminal of the first amplifier device and the first type outputterminal of the second amplifier device are electrically separated inthe output circuit, and the second type output terminal of the firstamplifier device second type output terminal of the second amplifierdevice are electrically separated in the output circuit.

By connecting equivalent nodes in the two branches of a amplifiers withseparated ground planes, having different potentials enables toamplifier devices to be run as push-pull amplifiers with a low impedanceat common mode over a very large bandwidth without effecting theimpedance at differential mode. Operation with higher efficiency andless distortion over a larger bandwidth is enabled.

If the amplifier devices are run in a differential mode, the amplifierdevices will output both a differential mode and a common mode, wherethe common mode may be terminated in an impedance that can be a lowreactive impedance. The differential mode can be terminated, for examplein a load resistance.

According to some aspects, each connection comprises a direct current,DC, blocking component.

This way, an efficient DC bias of the amplifier devices is enabled.

According to some aspects, each connection constitutes a short-circuitat a pre-determined signal frequency band.

In this way, the connections are transferring signals for a desiredfrequency band while still enabling an efficient DC bias of theamplifier devices.

According to some aspects, the amplifier devices are adapted to be runin a differential mode and in a common mode, where, for a certainfrequency band, a majority of the current supplied by the amplifierdevices runs via the connections when the amplifier devices are a run inthe common mode.

According to some aspects, the input circuit comprises an input balunand one input matching network for each input signal.

This means that a balanced signal is generated by the input balun thatis integrated into the input circuit.

According to some aspects, the input balun is constituted by a broadsidecoupled line input where a ground plane is provided between thebroadside coupled lines of the line input to create two microstriplines.

In this way, the input balun can be formed by means of microstripconductors.

According to some aspects, the input circuit comprises transmissionlines running from the input balun towards input matching networks. Theamplifier arrangement comprises a resistive component that connectsground potentials of each transmission line.

In this way, undesired modes propagating between the ground planes canbe suppressed.

According to some aspects, the input circuit comprises twodigital-to-analogue converters (DACs) that are connected to therespective terminals of the amplifier devices.

According to some aspects, the DACs are adapted to receive signal inputby means of corresponding optical couplers.

According to some aspects, the input circuit comprises two opticalcouplers that are connected to the respective terminals of the amplifierdevices.

This way, the input circuit can be realized in alternative ways.

According to some aspects, the output circuit comprises at least oneoutput matching network.

According to some aspects, the connections are connected to at leastpartly constitute an output balun that is connected to the outputmatching network.

This way, the connections are utilized to create a wideband balun withlow impedance at common mode, or as a mean to achieve common mode shortcircuit at nodes separated from the output balun, e.g. in a distributedamplifier. The matching of the amplifier devices can be made after theoutput balun.

According to some aspects, the second type output terminals of theamplifier devices are connected to electrically separated ground planes.

According to some aspects, the separated ground planes are formed bymeans of a slot in a ground plane, the slot having a first longitudinalside and a second longitudinal side. The first type output terminal ofthe first amplifier device and the second type output terminal of thesecond amplifier device are connected to the ground plane along thefirst longitudinal side of the slot, and the second type output terminalof the first amplifier device and the first type output terminal of thesecond amplifier device are connected to the ground plane on an oppositeside of the slot, along the second longitudinal side of the slot.

According to some aspects, the output circuit comprises transmissionlines running from the output matching network to an output balun, wherethe amplifier arrangement comprises a resistive component that connectsground potentials of each transmission line.

In this way, undesired modes propagating between the ground planes canbe suppressed. Furthermore, the amplifier devices can be separated fromthe output balun which is suitable in implementations where matchingand/or impedance transformation is preferred between the amplifierdevices and the output balun, e.g. in a distributed amplifier.

This object is also obtained by means of methods that are associatedwith the above advantages.

BRIEF DESCRIPTION OF THE DRAWINGS

The present disclosure will now be described more in detail withreference to the appended drawings, where:

FIG. 1 shows schematics of a prior art push-pull amplifier arrangement;

FIG. 2A shows schematics of a general push-pull amplifier arrangementaccording to the present disclosure in a differential mode;

FIG. 2B shows schematics of a general push-pull amplifier arrangementaccording to the present disclosure in a common mode;

FIG. 3A shows schematics of a push-pull amplifier arrangement accordingto a first example in a differential mode;

FIG. 3B shows schematics of a push-pull amplifier arrangement accordingto a first example in a common mode;

FIG. 4A shows schematics of a push-pull amplifier arrangement accordingto a second example in a differential mode;

FIG. 4B shows schematics of a push-pull amplifier arrangement accordingto a second example in a common mode; and

FIG. 5 shows details of an input balun of a push-pull amplifierarrangement according to the first example;

FIG. 6A shows a simplified first example of a realization of a push-pullamplifier arrangement in a differential mode, where the output balun isformed in a slot;

FIG. 6B shows the simplified first example of FIG. 6A in a common mode;

FIG. 7 shows a simplified second example of a realization of a push-pullamplifier arrangement in a common mode; and

FIG. 8 shows a flowchart for methods according to the presentdisclosure.

DETAILED DESCRIPTION

Aspects of the present disclosure will now be described more fullyhereinafter with reference to the accompanying drawings. The differentdevices, systems, computer programs and methods disclosed herein can,however, be realized in many different forms and should not be construedas being limited to the aspects set forth herein. Like numbers in thedrawings refer to like elements throughout.

The terminology used herein is for describing aspects of the disclosureonly and is not intended to limit the invention. As used herein, thesingular forms “a”, “an” and “the” are intended to include the pluralforms as well, unless the context clearly indicates otherwise.

With reference to FIG. 2A, there is a schematic of a general setup foran n-type or p-type push-pull amplifier arrangement 1 comprising a firstamplifier device 2 and a second amplifier device 3. This general setupwill be used for initially describing the present disclosure. Theamplifier devices 2, 3 are of class B, class AB or any other suitabletype which can be biased in such a way so that each amplifier deviceonly conducts during approximately one half cycle of an input signalwaveform.

Simplified, for such biasing, in a differential mode, at the carrierfrequency the signals from the amplifier devices are intended to beadded in phase with each other such that a useful signal is output. In acommon mode, even harmonics or mixing products, which are the onlyharmonics present, are intended to be added 180° out of phase such thatthere is no output signal for these signals. It is to be noted that thedifferential mode and the common mode normally occur simultaneously.

Each amplifier device 2, 3 is connected to an input circuit 8, and has afirst type output terminal 4, 6, marked as positive (+) and a secondtype output terminal 5, 7, marked as negative (−), where the outputterminals 4, 6; 5, 7 are connected to an output circuit 9. According tothe present disclosure, the first type output terminal 4 of the firstamplifier device 2 is connected to the second type output terminal 7 ofthe second amplifier device 3 by means of a first connection 10, and thefirst type output terminal 6 of the second amplifier device 3 isconnected to the second type output terminal 5 of the first amplifierdevice 2 by means of a second connection 11. Furthermore, the outputnetwork 9 should electrically separate the second type output terminal 5of the first amplifier device 2 from the second type output terminal 7of the second amplifier device 3. Correspondingly, the output network 9should electrically separate the first type output terminal 4 of thefirst amplifier device 2 from the first type output terminal 6 of thesecond amplifier device 3. In this context, the term electricallyseparate refers to a practical electrical separation that for examplecan be accomplished by means of galvanic separation or by means oftransmission lines that are connected to each other at a certain lengthfrom the output terminals 4, 5; 6, 7.

Although an analogue balun will be disclosed as being comprised in theinput circuit 8 in the following examples, generally, the input circuit8 is adapted to create input signal which are 180° out of phase witheach other, and can be based on analogue, digital and/or optical circuitelements. This means that the input circuit 8 can be adapted to createan input signal in a digital manner as will be discussed briefly below.

In this manner, separated ground planes are provided for the amplifierdevices 2, 3, providing a common mode short-circuit since all currentruns in the connections 10, 11 as shown in FIG. 2B. This creates a lowimpedance at the common mode over a relatively large bandwidth withouteffecting the impedance at differential mode, as illustrated in FIG. 2A.The amplifier arrangement 1 can operate with higher efficiency and lessdistortion over a larger bandwidth. The connections 10, 11 can beutilized to create a wideband output balun in the output circuit 9 withlow impedance at common mode, or as a mean to achieve common modeshort-circuit at nodes separated from the balun, e.g. in a distributedamplifier.

Note that the described connections in the ideal case are assumed tohave zero length and zero parasitics. In a real implementation, that isof course not possible, but the connections should be made as short aspossible. Also note that FIG. 2A and FIG. 2B illustrates the principleof the connections 10, 11 at AC frequencies. For desired properties atDC there might be a need of DC-blocks which are not included, but willbe included in further more detailed examples. In all examples, there isof course suitable DC feed circuitry. For reasons of clarity, this isnot shown in the Figures, being of obvious character and in itself notbeing a part of the present disclosure.

In FIG. 3A and FIG. 3B, illustrating a first detailed example, theconnections 110, 111 are connected such that an output balun 116 isformed, having a wideband low impedance at a common mode that is shownin FIG. 3B. According to some aspects, there is an output matchingnetwork 115 placed after the output balun 116, where the output matchingnetwork 115 further is connected to a load R_(L). In this case, anoutput circuit 109 comprises the output balun 116 and the outputmatching network 115. According to some aspects, an input circuit 108comprises an input balun 112 and one input matching network 113A, 113Bfor each input signal. Each input signal is transmitted from the inputbalun 112 to the corresponding input matching network 113A, 113B bymeans of input transmission lines TL1_(in), TL2_(in). The amplifierdevices 102, 103 are of the same type, each comprising a source terminalS, a gate terminal G and a drain terminal D. The output balun 116 isformed by connecting the drain terminals D and the connections 110, 111in the output circuit 109 such that an unbalanced connection is formed,the connections 110, 111 at least partly being comprised in the outputbalun 116. The source terminals S of the amplifiers devices 102, 103 areelectrically separated in the output circuit 109 by means of the outputbalun 116. The drain terminals D of the amplifiers devices 102, 103 arealso electrically separated in the output circuit 109 by means by meansof the output balun 116. The unbalanced connection passes the outputmatching network and is connected outside the output circuit 109 via theload resistance R_(L).

As an alternative, as indicated above, the input circuit 108 couldinstead be constituted by two digital-to-analogue converters (DACs) thatare directly connected to the respective source terminal S and gateterminal G of the amplifier devices 102, 103. This is illustrated inFIG. 2A and FIG. 2B, where the input circuit 8 according to some aspectscomprises a first DAC 20A that is connected to the first amplifierdevice 2, optionally being fed via a first optical coupler 21A.Correspondingly, the input circuit 8 then also comprises a second DAC20B that is connected to the second amplifier device, optionally beingfed via a second optical coupler 21B. In this case, there is no separateinput balun. The optical couplers 21A, 21B are used when the digitalinput signal is an optical signal.

According to some further aspects, there are no DAC:s but the inputcircuit 8 comprises a first optical coupler 21A and a second opticalcoupler 21B, where the optical couplers 21A, 21B are connected to therespective terminals of the amplifier devices 2, 3. In this case, theamplifier devices 2, 3 are fed analog signals directly via the opticalcouplers 21A, 21B.

The source terminals S are connected to input 117, 118 ground planesthat are sufficiently isolated from each other since the load R_(L)otherwise becomes short-circuited.

FIG. 3A illustrates the push-pull functionality at a differential mode,i.e. when the amplifier devices 102, 103 feed the output with signalsequal in amplitude but shifted 180° in phase. With this setup, thecurrents, which are illustrated with dotted arrows on an output sideonly, add in parallel, and the intrinsic impedances presented to theamplifier devices 102, 103 by the output matching network 115 shouldequal 0.5R_(opt), where R_(opt) is the optimum load presented to therespective intrinsic current source in the amplifier devices 102, 103,for a desired performance.

Between the intrinsic current source and the physical amplifier deviceoutput there are in practice normally some parasitics that results inthat the optimal load as seen from the amplifier device output differsfrom R_(opt), and can be referred to as intrinsic load.

FIG. 3B illustrates the push-pull functionality in a common mode. Thecurrents then become short-circuited and no current passes through theload R_(L). The impedances presented to the amplifier devices 102, 103should equal about 0Ω, i.e. short-circuit.

FIG. 4A and FIG. 4B, illustrating a second detailed example, show aconfiguration where there are two output matching networks 215A, 215Bwhich are connected between the amplifier devices 102, 103 and an outputbalun 216 via output transmission lines TL1_(out), TL2_(out) comprisingoutput ground planes 120, 121. According to some aspects, in the sameway as for the first detailed example, an input circuit 108 comprises aninput balun 112 and one input matching network 113A, 113B for each inputsignal. Each input signal is transmitted from the input balun 112 to thecorresponding input matching network 113A, 113B by means of inputtransmission lines TL1_(in), TL2_(in). The amplifier devices 102, 103are of the same type, each comprising a source terminal S, a gateterminal G and a drain terminal D. An output circuit 109′ comprises theoutput matching networks 215A, 215B, the output transmission linesTL1_(out), TL2_(out) and the output balun 216.

The source terminals S are connected to input ground planes 117, 118that are sufficiently isolated from each other since the load R_(L)otherwise becomes short-circuited.

FIG. 4A illustrates the push-pull functionality at a differential mode,i.e. when the amplifier devices 102, 103 feed the output with signalsequal in amplitude but shifted 180° in phase. With this setup, thecurrents, which are illustrated with dotted arrows on an output sideonly, add in phase, and the impedances presented to the amplifierdevices 102, 103 after the output matching networks 215A, 215B shouldequal 0.5R_(L), where R_(L) is the load resistance.

FIG. 4B illustrates the push-pull functionality in a common mode. Thecurrents then become short-circuited and no current passes through theload R_(L). The impedances presented to the amplifier devices 102, 103should equal 0Ω, i.e. short-circuit.

For both examples discussed above with reference to FIG. 3A, FIG. 3B,FIG. 4A and FIG. 4B, according to some aspects, each connection 110, 111comprises a direct current, DC, blocking component 114A, 114B thatprevent DC bias currents fed to the amplifier devices 102, 103 to runtowards the output matching network 115.

According to some aspects, there is one or multiple resistors 122connected between the input ground planes 117, 118 of the inputtransmission lines TL1_(in), TL2_(in), and for the example withreference to FIG. 4A and FIG. 4B there is also a resistor 119 connectedbetween the output ground planes 120, 121 of the output transmissionlines TL1_(out), TL2_(out). These resistors 122, 119 are used tosuppress potential modes propagating between these ground planes. Tosuppress unwanted propagation, possible coupling between the groundplanes 117, 118; 120, 121 should be minimized, and this can also beobtained by choosing a proper electrical length the transmission linesTL1_(in), TL2_(in), TL1_(out), TL2_(out). The output ground planes 120,121 are electrically connected in the output balun 216, but there can bea significant electrical distance between the resistor 119 connectedbetween the output ground planes 120, 121 of the output transmissionlines TL1_(out), TL2_(out) and the output balun 216. The outputtransmission lines TL1_(out), TL2_(out) have such an electrical lengththat the source terminals S of the amplifiers devices 102, 103 areelectrically separated in the output circuit 109′. The drain terminals Dof the amplifiers devices 102, 103 are electrically separated in theoutput circuit 109′ by means of galvanic separation and are connectedoutside the output circuit 109′ via the load resistance R_(L).

Although the transmission lines TL1_(in), TL2_(in), TL1_(out), TL2_(out)are illustrated as coaxial lines, other types of transmission lines maybe used such as for example microstrip lines or strip lines.

According to some aspects, the input balun 112 can comprise a digitalarrangement that can be adapted to generate an input signal digitally.In the FIGS. 2A, 2B, 3A, 3B, 4A, 4B and 5 an input port Pin isindicated. If an input signal is generated in the input circuit 8 or inthe input balun 112, there is no need for a separate input port Pin.

FIG. 5 corresponds to the configuration of FIG. 3A and FIG. 3B. In thisexample, according to some aspects, the input balun 112 consist of abroad side coupled line input 320 where a ground plane 317 is providedbetween the broad side coupled lines of the line input 320 to create twomicrostrip lines 321, 322 on each side of a slot. According to somefurther aspects, the microstrip lines 321, 322 each have acharacteristic impedance that according to some aspects can be 50Ω.Furthermore, at a differential mode, the impedances presented to theamplifier devices 102, 103 by the output matching network 115 shouldequal 100Ω. Other values of the characteristic impedance are of courseconceivable.

According to some further aspects, from FIG. 3A and FIG. 3B it followsthat the source terminals S of the amplifier devices 102, 103 should beconnected to separated ground planes. In a PCB-design, such separationcan be achieved by making a sufficiently large slot 430 in a groundplane as schematically illustrated in FIG. 6A, illustrating adifferential mode, in FIG. 6B, illustrating a common mode. Note that theschematics of FIG. 6A and FIG. 6B is simplified to illustrate theprinciple of the implementation and e.g. DC-blocks are omitted. Thedrain D and the source S terminals of each amplifier devices 402, 403are connected to opposite sides of the slot 430 and that the output loadR_(L) is placed across the slot 430. As illustrated in FIG. 6A, allcurrents passes thru the load R_(L) at differential mode, whereas, asillustrated in FIG. 6B, no currents passes thru the load R_(L) in commonmode. The currents are indicated with dotted arrows.

More in detail, the slot 430 having a slot width w_(s) is formed in aground plane 431, the slot having a first longitudinal side 432 and asecond longitudinal side 433, where the first type output terminal D ofthe first amplifier device 402 and the second type output terminal S ofthe second amplifier device 403 are connected to the ground plane 431along the first longitudinal side 432 of the slot 430. The slot has afirst end part 441 with increased slot width w_(si) and a second endpart 442 with the increased slot width w_(si). By means of thisincreased slot width w_(si), the coupling between opposite sides of theslot 430 is reduced. This shape of the slot 430 makes it possible tofairly accurate regard it as an inductive connection, increasing theinductance and lowering the resonance frequency. According to someaspects, the electrical length from the center of the slot 430 to eachshort-circuited edge 445, 446 is kept close to 90° at the centerfrequency. According to other aspects, i.e. when having a non neglibledevice drain-to-source capacitance, the electrical length from thecenter of the slot 430 to each short-circuited edge 445, 446 is keptbelow 90° at the center frequency

The first type output terminals D of the amplifier devices 402, 403 areconnected to the ground plane 431 on an opposite side of the slot 430,along the second longitudinal side 433 of the slot 430. More in detail,the first type output terminal D of the first amplifier device 402 isconnected to ground at the other side of the slot 430 by means of afirst conductor 443 that passes the slot 430 at the opposite side.Correspondingly, the first type output terminal D of the secondamplifier device 402 is connected to ground at the other side of theslot 430 by means of a second conductor 444 that passes the slot 430 atthe opposite side. The conductors 443, 444 have an electrical lengththat falls below an electrical length of 90° at the center frequencywith a large margin, and practically these conductors 443, 444 barelycross the slot 430, i.e. they cross the slot 430 but do not continue anyfarther than, at least not more than necessary. According to someaspects, the conductors 443, 444 have an electrical length that at leastequals the slot width w_(s) and should fall below an electrical lengthof 20°, preferably fall below an electrical length of 10°, and even morepreferably fall below an electrical length of 5° at a center frequencyof a desired frequency band. In case the conductors 443, 444 aregrounded by means of via connections, the via length is included in thelength of the conductors 443, 444 that according to some aspects areconstituted by microstrip or stripline conductors. A desired frequencyband is a frequency band for which the amplifier arrangement is intendedto be operational.

The slot 430 will act as a short-circuited slot line that should be madeas wide as possible in order to avoid unwanted mode propagation and witha proper length for the targeted bandwidth.

FIG. 7 shows an alternative of how the slot in FIG. 6B can be configuredfor an amplifier arrangement 700. The common mode is shown in FIG. 7 ,but the arrangement of FIG. 7 is of course applicable for thedifferential mode as well. Here, the left side of the slot 730 isterminated in an open circuit at an edge 750 of the circuit board,resulting in a potentially larger differential mode bandwidth comparedto the configuration in FIGS. 6A and 6B. The slot here only has one endpart 742 with a maximum increased slot width w_(si), and in this examplethe end part 742 has a circular shape. Of course, any shape of the endparts is conceivable for all types of slots, for examples steppedstructures where the width increases and/or decreases in steps to amaximum value, or a tapered part where the width increases continuouslyto a maximum value, where the maximum value can be anywhere in the endpart. The slot can have any type of shape, where different end parts canhave different shapes.

Other types of slots are of conceivable, according to some aspects, theslot can be arranged in one or more metallization layers, the slot beinglongitudinally divided over the slot gap. The microstrip/striplineconductors can be arranged in one, two or three other metallizationlayer. The microstrip/stripline conductors can thus be made in the samemetal layer. In the case of the slot being formed in two or moremetallization layers, the conductors can run between these metallizationlayers.

According to some aspects, the ground symbols in FIG. 6A, FIG. 6B andFIG. 7 denote a local ground or local reference plane, where the slotseparates the grounds.

With reference to the general setup outlined in FIG. 2A and FIG. 2B, itis a main concept of the present disclosure that two amplifier devices2, 3 of the same type are run in a push-pull configuration, where afirst type output terminal 4 of a first amplifier device 2 is connectedto a second type output terminal 7 of a second amplifier device 3, andwhere the second type output terminal 5 of the first amplifier device 2is connected to the first type output terminal 6 of the second amplifierdevice 3. This provides separated ground planes at the output of theamplifier devices, and enables

The amplifier devices 2, 3 can be of class B, class AB or any othersuitable type which can be biased in such a way so that each amplifierdevice only conducts during approximately one half cycle of an inputsignal waveform. The amplifier devices 2, 3 can for example be of n-typeor p-type. In the general case, no input baluns are required.

In practice, the term short-circuit relates to a low impedanceconnection which according to some aspects is present for one or morefrequency bands.

It is to be noted that the connections 10, 11; 110, 111; 410, 411 onlyare schematically indicated and are adapted to electrically connect afirst type output terminal 4, D of the first amplifier device 2, 102,202 to a second type output terminal 7, S of the second amplifier device3, 103, 203, and to connect the first type output terminal 6, D of thesecond amplifier device 3, 103, 203 to the second type output terminal5, S of the first amplifier device 2, 102, 202.

The term electrically separated refers to an electrical separation thatcan be accomplished in several ways as discussed above.

The present disclosure relates to an amplifier arrangement 1, 100, 200comprising a first amplifier device 2, 102, 202 and a second amplifierdevice 3, 103, 203, each amplifier device 2, 3; 102, 103; 202, 203 beingconnected to an input circuit 8, 108. Each amplifier device 2, 3; 102,103; 202, 203 has a first type output terminal 4, 6; D and a second typeoutput terminal 5, 7; S where the output terminals 4, 6, D; 5, 7, S areconnected to an output circuit 9, 109, 109′. The first type outputterminal 4, D of the first amplifier device 2, 102, 202 is connected tothe second type output terminal 7, S of the second amplifier device 3,103, 203 by means of a first connection 10, 110, and the first typeoutput terminal 6, D of the second amplifier device 3, 103, 203 isconnected to the second type output terminal 5, S of the first amplifierdevice 2, 102, 202 by means of a second connection 11, 111. The firsttype output terminal 4, D of the first amplifier device 2, 102, 202 andthe first type output terminal 6, D of the second amplifier device 3,103, 203 are electrically separated in the output circuit 9, 109, 109′,and the second type output terminal 5, S of the first amplifier device2, 102, 202 second type output terminal 7, S of the second amplifierdevice 3, 103, 203 are electrically separated in the output circuit 9,109, 109′.

According to some aspects, each connection 110, 111 comprises a directcurrent, DC, blocking component 114A, 114B.

According to some aspects, each connection 10, 11; 110, 111 constitutesa short-circuit at a pre-determined signal frequency band.

According to some aspects, the amplifier devices 2, 3, 102, 103; 202,203 are adapted to be run in a differential mode and in a common mode,where, for a certain frequency band, a majority of the current suppliedby the amplifier devices 2, 3; 102, 103; 202, 203 runs via theconnections 10, 11; 110, 111 when the amplifier devices 2, 3; 102, 103;202, 203 are a run in the common mode.

According to some aspects, the input circuit 108 comprises an inputbalun 112 and one input matching network 113A, 113B for each inputsignal.

According to some aspects, the input balun 112 is constituted by abroadside coupled line input 320 where a ground plane 317 is providedbetween the broadside coupled lines of the line input 320 to create twomicrostrip lines 321, 322.

According to some aspects, the input circuit 108 comprises transmissionlines TL1_(in), TL2_(in) running from the input balun 112 towards inputmatching networks 113A, 113B, where the amplifier arrangement 100, 200comprises a resistive component 122 that connects ground potentials ofeach transmission line TL1_(in), TL2_(in).

According to some aspects, the input circuit 8 comprises twodigital-to-analogue converters 20A, 20B (DACs) that are connected to therespective terminals of the amplifier devices 2, 3.

According to some aspects, the DACs 20A, 20B, are adapted to receivesignal input by means of corresponding optical couplers 21A, 21B.

According to some aspects, the input circuit 8 comprises two opticalcouplers 21A, 21B, that are connected to the respective terminals of theamplifier devices 2, 3.

According to some aspects, the output circuit 109, 109′ comprises atleast one output matching network 115, 215A, 215B.

According to some aspects, the connections 110, 111 are connected to atleast partly constitute an output balun 116 that is connected to theoutput matching network 115.

According to some aspects, the second type output terminals S of theamplifier devices 402, 403; 402, 403 are connected to electricallyseparated ground planes.

According to some aspects, the separated ground planes are formed bymeans of a slot 430 in a ground plane 431, the slot having a firstlongitudinal side 432 and a second longitudinal side 433.

The first type output terminal D of the first amplifier device 402 andthe second type output terminal S of the second amplifier device 403 areconnected to the ground plane 431 along the first longitudinal side 432of the slot 430. The second type output terminal S of the firstamplifier device 402 and the first type output terminal D of the secondamplifier device 403 are connected to the ground plane 431 on anopposite side of the slot 430, along the second longitudinal side 433 ofthe slot 430.

According to some aspects, the output circuit 109′ comprisestransmission lines TL1_(out), TL2_(out) running from the output matchingnetwork 215A, 215B to an output balun 216, where the amplifierarrangement 200 comprises a resistive component 119 that connects groundpotentials of each transmission line TL1_(out), TL2_(out).

With reference to FIG. 8 , the present disclosure also relates to amethod for configuring an amplifier arrangement 1, 100, 200, the methodcomprising providing S100 a first amplifier device 2, 102, 202 and asecond amplifier device 3, 103, 203, each amplifier device 2, 3; 102,103; 202, 203 having a first type output terminal 4, 6; D and a secondtype output terminal 5, 7; S. The method further comprises connectingS200 the amplifier devices 2, 3; 102, 103; 202, 203 to an input circuit8, 108, and connecting S300 the output terminals 4, 6, D; 5, 7, S to anoutput circuit 9, 109, 109′. The method also comprises connecting S400the first type output terminal 4, D of the first amplifier device 2,102, 202 to the second type output terminal 7, S of the second amplifierdevice 3, 103, 203 using a first connection 10, 110, and connecting S500the first type output terminal 6, D of the second amplifier device 3,103, 203 to the second type output terminal 5, S of the first amplifierdevice 2, 102, 202 by using a second connection 11, 111.

The first type output terminal 4, D of the first amplifier device 2,102, 202 and the first type output terminal 6, D of the second amplifierdevice 3, 103, 203 are electrically separated in the output circuit 9,109, 109′, and where the second type output terminal 5, S of the firstamplifier device 2, 102, 202 second type output terminal 7, S of thesecond amplifier device 3, 103, 203 are electrically separated in theoutput circuit 9, 109, 109′.

According to some aspects, the method comprises providing a directcurrent, DC, blocking component 114A, 114B at each connection 110, 111.

According to some aspects, each connection 10, 11; 110, 111 constitutesa short-circuit at a pre-determined signal frequency band.

According to some aspects, the amplifier devices 2, 3, 102, 103; 202,203 are used for running in a differential mode and in a common mode,where, for a certain frequency band, a majority of the current suppliedby the amplifier devices 2, 3; 102, 103; 202, 203 runs via theconnections 10, 11; 110, 111 when the amplifier devices 2, 3; 102, 103;202, 203 are a run in the common mode.

According to some aspects, the method comprises providing an input balun112 and one input matching network 113A, 113B for each input signal atthe input circuit 108.

According to some aspects, the input balun 112 is constituted by abroadside coupled line input 320 where a ground plane 317 is providedbetween the broadside coupled lines of the line input 320 to create twomicrostrip lines 321, 322.

According to some aspects, the method comprises providing transmissionlines TL1_(in), TL2_(in), running from the input balun 112 towards inputmatching networks 113A, 113B, at the input circuit 108, and providing aresistive component 122 that connects ground potentials of eachtransmission line TL1_(in), TL2_(in).

According to some aspects, the method comprises providing twodigital-to-analogue converters 20A, 20B (DACs) at the input circuit 8,the DACs 20A, 20B being connected to the respective terminals of theamplifier devices 2, 3.

According to some aspects, the output circuit 109, 109′ comprises atleast one output matching network 115, 215A, 215B.

According to some aspects, the method comprises connecting theconnections 110, 111 to at least partly constitute an output balun 116that is connected to the output matching network 115.

According to some aspects, the method comprises connecting the secondtype output terminals S of the amplifier devices 402, 403; 402, 403 toelectrically separated ground planes.

According to some aspects, the method comprises providing transmissionlines TL1_(out), TL2_(out), running from the output matching network215A, 215B towards an output balun 216, and providing a resistivecomponent 119 that connects ground potentials of each transmission lineTL1_(out), TL2_(out).

The present disclosure is not limited to the above, but may vary freelywithin the scope the appended claims. For example, according to someaspects, the slot can have many other shapes than the ones disclosed.

According to some aspects, the amplifier arrangement 1, 100, 200 isadapted to run the amplifier devices 2, 3; 102, 103; 202, 203 in adifferential mode, where the amplifier devices 2, 3; 102, 103; 202, 203will output both a differential mode and a common mode. According to thepresent disclosure, the common mode will be terminated in an impedancethat can be a low reactive impedance. The differential mode can beterminated in a load R_(L).

1. An amplifier arrangement comprising: a first amplifier device; and asecond amplifier device, wherein each amplifier device is connected toan input circuit, each amplifier device has a first type output terminaland a second type output terminal where the output terminals areconnected to an output circuit, the first type output terminal of thefirst amplifier device is connected to the second type output terminalof the second amplifier device by means of a first connection, the firsttype output terminal of the second amplifier device is connected to thesecond type output terminal of the first amplifier device by means of asecond connection, the first type output terminal of the first amplifierdevice and the first type output terminal of the second amplifier deviceare electrically separated in the output circuit, and the second typeoutput terminal of the first amplifier device and the second type outputterminal of the second amplifier device are electrically separated inthe output circuit.
 2. The amplifier arrangement of claim 1, whereineach connection comprises a direct current (DC) blocking component. 3.The amplifier arrangement of claim 1, wherein each connectionconstitutes a short-circuit at a pre-determined signal frequency band.4. The amplifier arrangement of claim 1, wherein the amplifier devicesare adapted to be run in a differential mode and in a common mode,where, for a certain frequency band, a majority of the current suppliedby the amplifier devices runs via the connections when the amplifierdevices are a run in the common mode.
 5. (canceled)
 6. The amplifierarrangement of claim 1, wherein the input circuit comprises an inputbalun and one input matching network for each input signal, and theinput balun is constituted by a broadside coupled line input where aground plane is provided between the broadside coupled lines of the lineinput to create two microstrip lines.
 7. The amplifier arrangement ofclaim 1, wherein the input circuit comprises an input balun and oneinput matching network for each input signal, and the input circuitcomprises transmission lines (TL1_(in), TL2_(in)) running from the inputbalun towards input matching networks, where the amplifier arrangementcomprises a resistive component that connects ground potentials of eachtransmission line (TL1_(in), TL2_(in)).
 8. The amplifier arrangement ofclaim 1, wherein the input circuit comprises two digital-to-analogueconverters that are connected to the respective terminals of theamplifier devices, and the DACs are adapted to receive signal input bymeans of corresponding optical couplers.
 9. (canceled)
 10. The amplifierarrangement of claim 1, wherein the input circuit comprises two opticalcouplers that are connected to the respective terminals of the amplifierdevices.
 11. The amplifier arrangement of claim 1, wherein the outputcircuit comprises at least one output matching network, and theconnections are connected to at least partly constitute an output balunthat is connected to the output matching network.
 12. (canceled)
 13. Theamplifier arrangement of claim 1, wherein the second type outputterminals of the amplifier devices are connected to electricallyseparated ground planes, and the separated ground planes are formed bymeans of a slot in a ground plane, the slot having a first longitudinalside and a second longitudinal side, where the first type outputterminal of the first amplifier device and the second type outputterminal of the second amplifier device are connected to the groundplane along the first longitudinal side of the slot, and where thesecond type output terminal of the first amplifier device and the firsttype output terminal of the second amplifier device are connected to theground plane on an opposite side of the slot, along the secondlongitudinal side of the slot.
 14. (canceled)
 15. The amplifierarrangement of claim 1, wherein the output circuit comprises at leastone output matching network, and the output circuit comprisestransmission lines (TL1_(out), TL2_(out)) running from the outputmatching network to an output balun, where the amplifier arrangementcomprises a resistive component that connects ground potentials of eachtransmission line (TL1_(out), TL2_(out)).
 16. A method for configuringan amplifier arrangement, the method comprising: providing a firstamplifier device and a second amplifier device, each amplifier devicehaving a first type output terminal and a second type output terminal;connecting the amplifier devices to an input circuit; connecting theoutput terminals to an output circuit; connecting the first type outputterminal of the first amplifier device to the second type outputterminal of the second amplifier device using a first connection; andconnecting the first type output terminal of the second amplifier deviceto the second type output terminal of the first amplifier device byusing a second connection, where the first type output terminal of thefirst amplifier device and the first type output terminal of the secondamplifier device are electrically separated in the output circuit, andthe second type output terminal of the first amplifier device and thesecond type output terminal of the second amplifier device areelectrically separated in the output circuit.
 17. The method of claim16, wherein the method comprises providing a direct current, DC,blocking component at each connection.
 18. The method of claim 16,wherein each connection constitutes a short-circuit at a pre-determinedsignal frequency band.
 19. The method of claim 16, wherein the amplifierdevices are used for running in a differential mode and in a commonmode, where, for a certain frequency band, a majority of the currentsupplied by the amplifier devices runs via the connections when theamplifier devices are a run in the common mode.
 20. (canceled)
 21. Themethod of claim 16, wherein the method comprises providing an inputbalun and one input matching network for each input signal at the inputcircuit, and the input balun is constituted by a broadside coupled lineinput where a ground plane is provided between the broadside coupledlines of the line input to create two microstrip lines.
 22. The methodof claim 16, wherein the method comprises providing an input balun andone input matching network for each input signal at the input circuit,and the method comprises providing transmission lines (TL1_(in),TL2_(in)), running from the input balun towards input matching networks,at the input circuit, and providing a resistive component that connectsground potentials of each transmission line (TL1_(in), TL2_(in)). 23.The method of claim 16, wherein the method comprises providing twodigital-to-analogue converters, DACs, at the input circuit, the DACsbeing connected to the respective terminals of the amplifier devices.24. The method of claim 16, wherein the output circuit comprises atleast one output matching network, the method comprises connecting theconnections to at least partly constitute an output balun that isconnected to the output matching network, and the method comprisesproviding transmission lines (TL1_(out), TL2_(out)), running from theoutput matching network towards an output balun, and providing aresistive component that connects ground potentials of each transmissionline (TL1_(out), TL2_(out)).
 25. (canceled)
 26. The method of claim 16,wherein the method comprises connecting the second type output terminalsof the amplifier devices to electrically separated ground planes, andthe separated ground planes are formed by means of a slot in a groundplane, the slot having a first longitudinal side and a secondlongitudinal side, where the first type output terminal of the firstamplifier device and the second type output terminal of the secondamplifier device are connected to the ground plane along the firstlongitudinal side of the slot, and where the second type output terminalof the first amplifier device and the first type output terminal of thesecond amplifier device are connected to the ground plane on an oppositeside of the slot, along the second longitudinal side of the slot. 27.(canceled)
 28. (canceled)